From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Development and suggested improvements for the EAC Engine X.9770.
| Identifier | ExFiles\Box 72\4\ scan0179 | |
| Date | 11th May 1924 | |
| X9770 SECRET To RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design}.HS{Lord Ernest Hives - Chair}) FROM R.{Sir Henry Royce} c. to CJ. Wor.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} RE. EAC. ENGINE. X.9770 To produce EAC.2. it is necessary to get this engine perfected. I have seen the reports of the conference but had not heard the result of the various tests which were put in hand for the investigations of the peculiarities observed with this engine. It is so nearly on the lines of the Goshawk engine, and it at first appeared so promising that it is disappointing to hear it will take considerable time to perfect it sufficiently for sale. (1) I have had no report regarding the effect of the longer con. rods. According to E.{Mr Elliott - Chief Engineer} these should not reduce the source of over-run vibration more than 10%, so are hardly worth waiting for, and I suggested that we ought to be able to get such a 10% by decreasing the weight of the piston and little ends by a like amount. (2) The other point is detonations and coarseness. These two go together with increase in compression ratio or actual compression. I have not heard of this engine being reduced to the compression ratio of the 40/50. It would seem that at the conference the impression was given that the engine was a failure, but naturally everything that is made can be improved afterwards, by my impression is we have not yet tried to make the best of what should make a good thing judging from the Goshawk engine, and we must expect an additional sensation from a more powerful engine. We are fighting for about 120 HP. from the same engine. as about 80 HP. Even then we are not putting it on equal terms. Therefore retest the engine with 10% of weight taken from the reciprocating parts and the compressing pressure reduced to same as the one you are comparing it with. In the meantime prepare the improvement which we have suggested. (1) Longer rods if test shews an advantage. (2) More rigid support in frame and stiffer frame, if tests shew an advantage. (I believe this may be what is needed.) (3) More favourable position of 2nd. sparking plug if we can find a practical one. (4) Aluminium head which ought easily to fit present engine if thought reliable, and test out an improvement. R.{Sir Henry Royce} | ||